The subject matter disclosed herein relates generally to gas turbine engines and, more particularly, to methods and apparatus for controlling the operation of gas turbine engines.
Some gas turbine engines may include a compressor section, a combustor section, and at least one turbine section. The compressor compresses air, which is mixed with fuel and channeled to the combustor. The mixture is then ignited, generating hot combustion gases. The combustion gases are channeled to the turbine, which extracts energy from the combustion gases for powering the compressor, as well as producing useful work to power a load, such as an electrical generator, or to propel an aircraft in flight.
In some gas turbine engines, certain control parameters may be adjusted based upon the operating status of the engine. For example, in a gas turbine engine configured to propel an aircraft or drive an electrical generator, the angular position of variable stator vanes in the compressor may be configured to vary with corrected core speed, such as according to predetermined schedule. The predetermined schedule may be established such that the engine should produce at least a minimum expected amount of thrust or power output and maintain a minimum required stall margin throughout the operating envelope, while accounting for a full range of engine-to-engine manufacturing quality variations, deterioration of engine components over many years of operation in service, control sensor measurement errors, changes in operating conditions (e.g., humidity), and the like. As a result, and by design, the engine may produce a reduced level of thrust or power output or suboptimal level of efficiency, below its potential capability, in many circumstances.
The problem: Operation of gas turbines at suboptimal control parameter settings due to the use of a predetermined schedule for certain control parameters may impact fuel efficiency, operating temperatures, engine life, exhaust emissions, etc.